Chemical investigation on stereoselective synthesis and properties of modified DNA oligomers has been done in order to obtain the information about the elucidation of DNA function systems and development of new type of medicines. During this study, the apparatus such as spinning concentrator, and electrophoretic equipments were efficiently employed for isolation and characterization of the modified DNA molecules. The results of our investigation are summaried as follows :1. Hybridization of functional heterocyclic compounds, flavin, 5-deazaflavin, viologen, with DNA oligomer was effectively achieved in covalent phosphoramidate, using alkylamine as a linker. On the basis of this approach, several modified DNA oligomers have been synthesized, in which the functional hoterocyclic compounds were introduced at the desired site of the sequence.2. After characterization, the stability of the duplex with their comlementary strands was examined. Subsequently, function and capabilities (intercal
… Moreator, fluorescence-marker, redox and local cleavage reactor) were investigated by means of UV, fluorescence, ESR spectra and HPLC analyses.3. The resistant reactivity of the above strand toward the conventional nuclease was observed at the modified site of the sequence.4. Some kinds of sulfur modified thymidine nucleotides were synthesized, which were incorporated into the desired site of the DNA sequence. The stability of the duplex was investigated by UV and CD spectra, and it turned out that both position of the sulfur and number of the modified base significantly influencedupon the stability and conformation of the duplex.5. Several attempts were made to achieve stereoselective internucleotide bond formation based on phosphoramidite approach under the controlled condition and with chiral auxiliaries. In spite of the effort, no satisfactory results were obtained and this subject remained as a future problem.6. The reductive repair of oxidatively damaged nucleosides was investigated and a proposal that glutathione and reduced coenzyme models might play an important role in the living systems, was made. Less